Technical Field
The present subject matter relates to a method for identifying contamination upon a lens of a stereoscopic camera. The subject matter further relates to a method for compensating for contamination upon a lens of said stereoscopic camera. Another aspect of the subject matter is a road surveillance facility utilizing a method for identifying contamination upon a lens of a stereoscopic camera. The subject matter is particularly advantageous in harsh environments, such as in close proximity of a busy road.
Background Art
Stereoscopic computer vision uses a stereoscopic camera, i.e. two slightly spaced apart cameras looking at the same area, to measure distances from the camera. Since the two cameras are spaced apart, they see the area from different angles and therefore render somewhat different images of the exposed area. The differences between the images from the two cameras can be used to calculate depth and distances. However, a stereoscopic system for measuring distances is highly vulnerable to contamination upon the camera lenses. A difference between the images caused by dirt may either be misinterpreted as a distance, or a distance may be overlooked or incorrectly measured due to the presence of contamination on the lenses. Despite this, stereoscopic systems sometimes operate in harsh environments where the camera lenses are exposed to contamination, e.g. in roadside systems, resulting in less functional systems.
EP 2 381 416 A1 describes a method reconstructing optically occluded parts of an image captured by a stereoscopic camera. The idea is to use the redundancy of the stereo camera pair to reconstruct the distorted images. The method renders just one reconstructed image out of the pair of images from the stereoscopic camera, and hence the depth information is lost.